Think about it. The cup is both a microphone and a speaker. It uses the same "hardware" for input and output of sound. Why, Buxton asked, couldn't the same principle apply to text on computers -- using a single device for both input and output of text rather than using input from a keyboard to produce output on a screen?

Buxton wasn't alone in recognizing an eventual fusion of the two. Fast-forward a couple decades -- and add myriad researchers and huge corporate R&D budgets -- and we have touch-screen keyboards on tablets and smartphones. Inputs and outputs share the same surface. The keyboard has fused with the screen, at least for some computing tasks.

But as anyone who's typed on a virtual keyboard -- or yelled at a voice-control app like Siri -- can attest, no current text input holds a candle to a traditional computer keyboard when it comes to comfort, speed and accuracy. Maybe eventually we'll connect computers to our neurons, but in the meantime, the simple yet highly functional electromechanical keyboard will be around -- and keep improving -- for some time.

Decades after its introduction in the mid-'80s, IBM's classic Model M remains a favorite for keyboard purists. Credit: BorgHunter.

Buxton, now a design guru at Microsoft Research, still closely examines old keyboards for forgotten tricks and technologies that could spawn new ways of thinking about how we enter information into a computer.

"Many of the great discoveries are right under our noses," he says when discussing the future of the keyboard. "A lot of the stuff that's emerging as new is rooted in things that have happened in the past -- and in some cases the really distant past."

Before we look at where computer keyboards might go in the future, then, let's look at where they've been.

Keying up the past

The evolution of the keyboard is not a clean timeline. Contributions to its look, feel and underpinning technologies sometimes draw from preceding models and other times from a far corner of the inventor's universe.

"The typewriter [keyboard] had all sorts of functions. The shift key was really big because you needed a big surface area to push down and raise the carriage up," says David Hill, vice president of design and user experience at computer manufacturer Lenovo. "There was a mechanical advantage required."

As far as direct influences on the modern computer keyboard, IBM's Selectric typewriter was one of the biggest. IBM released the first model of its iconic electromechanical typewriter in 1961, a time when being able to type fast and accurately was a highly sought-after skill.

Dag Spicer, senior curator at the Computer History Museum, notes that as the Selectric models rose to prominence, admins grew to love the feel of the keyboard because of IBM's dogged focus on making the ergonomics comfortable. "IBM's probably done more than anyone to find [keyboard] ergonomics that work for everyone," Spicer says. So when the PC hit the scene a decade or two later, the Selectric was largely viewed as the baseline to design keyboards for those newfangled computers you could put in your office or home.

In the late 1970s, companies like Cherry, Key Tronic and the Micro Switch division of Honeywell took off with their own approaches to mimicking the mechanical feel of a typewriter with the circuitry of a computer keyboard. "It was a real big deal back then," says Craig Gates, CEO of KeyTronicEMS, as the company is now called. "How the [keyboard] felt, how reliable it was, what speed could be achieved with a certain design of the switch."

Early switch designs

One of the first computer keyboard designs from the early '70s incorporated reed switches, which work with a magnet and two metal filaments. When the magnetic field gets close enough, it pulls the two filaments together and thus completes a circuit -- or, in the case of a key, a keystroke.

These keyboards housed circuit boards with 100 to 120 reed switches, each covered by a key. Underneath each key top was a tiny magnet. When someone depressed the key, the magnet made the filaments touch, thus generating an electrical signal for the desired character to type.

But filaments are fragile. (If you've dealt with busted holiday lights, you know this.) So these reed switch keyboards weren't reliable, Gates explains. If one broke or got out of alignment, or if dust obstructed the contact points, the key wouldn't work anymore -- and, unlike holiday lights, individual keys weren't easy to replace.

In addition, they were subject to microvibrations that opened and closed the switch a few times in a single keystroke, thus tricking the computer into thinking the letter had been pressed several times successively. (Microvibrations are still an issue in some keyboards, but microprocessors filter them out.)